History of Rheology Sample Clauses

History of Rheology. Scientists have studied fluids for a long time, reaching as far back as antiquity. Proba- xxx the earliest application of viscosity effects was performed around 1600 BCE by the Egyptian scientist Amenemhet, who made a correction to the drainage angle of a wa- ter clock to account for the viscosity change of water as the temperature changes [19]. In 1687, Xxxxx Xxxxxx stated a famous definition of the resistance of ideal fluids (now called viscosity): “The resistance which arises from the lack of slipperiness originating in a fluid – other things being equal – is proportional to the velocity by which the parts of the fluid are separated from each other” [67]. Xxxxxx characterized the class of fluids we now call Newtonian. The study of fluids, however, has not been a separate discipline until the early twentieth century. In 1924, a Plasticity Symposium (for the study of viscosity) was held at Lafayette College, Pennsylvania. Due to a high level of interest in the subject, the symposium was held several times in the following years. During the third symposium, in 1929, Xxxxxx X. Xxxxxxx and Xxxxxx Xxxxxx (both Lafayette College) suggested the creation of a dedicated discipline for the “study of the flow and the deformation of all forms of matter”, and suggested calling it “rhe- ology”. A committee, which included Xxxxxxx X. Xxxxxxxx, met on April 29th 1929 and decided to follow their suggestion. It was that same day that the field of rheol- ogy was coined [37]. The class of visco-plastic materials had still not received much attention during that time, and this did not change for the next few decades, until the early eighties. In 1983, a review by Bird et al. [23] appeared providing a list of several materials exhibiting a yield, making the scientific community more aware of the widespread presence of visco-plastic materials – and their potential applications. Since the appearance of this article, the interest in visco-plastic materials slowly in- creased and researchers started to study them more thoroughly. Attempts were made to model and simulate their flow. However, measuring the yield stress and finding the unyielded regions were still unresolved problems. At the same time, some researchers questioned the existence of visco-plasticity. Xxxxxx and Xxxxxxx [9] stated that if a material flows at high stresses it would also flow for low stresses, even though very slowly. This was however quickly disputed by many [7, 53, 88]. The appearance of the modificatio...